1. Field of the Invention
This invention relates to an image projection apparatus with the function of adjusting color tone or brightness, such as a projector, and an image output apparatus which outputs an image to be projected by the image projection apparatus.
2. Description of the Related Art
A conventional image projection apparatus, such as a projector, is provided with the function of adjusting the color tone of an image projected according to its use environment. For example, the colors of an iconic document or a product to be introduced using projected images may differ delicately from the real thing, depending on the color of the screen or wall onto which the image is projected, lighting environment, the state of the lamp, or the like. The color adjusting function is provided to adjust the difference between these colors.
For example, there are many situations that require color adjustments so that the image projected by an image projection apparatus can be recognized in the same colors as those of the original, such as the colors of organs or blood in a medical conference, the colors of perishable food, clothes, or cars in introducing products, or the color of litmus paper in science class at school.
One known function of adjusting color tone in an image projection apparatus is to adjust an arbitrary color according to the observer's taste in color by using a color adjusting bar (for example, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-15522). In the image projection apparatus disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-15522, a previously stored reference image and the parameters of the reference image (at least one of brightness, hue, and saturation) are used to project a plurality of kinds of different color images onto a screen. Then, on the basis of the observer's visual evaluation, the observer is caused to select the one closest to the reference color image from the color images, set the color image as a reference color image, and make a fine adjustment of arbitrary colors according to the user's taste in color by using a plurality of color adjusting bars, which causes an image based on the color-adjusted image signal to be projected onto the screen.